Picklino-bath



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COMPOSITIONS.

To all whom it may concern:

Cross Reference UNITED STATES PATENT orrrcn WILLIAM H. ALLEN, or nnrnorr, moment.

PICKLING-ZBATH.

1,321,182. No Drawing.

Be it known that I, WILLIAM H. ALLEN, a citizen of the United States, and residing at Detroit, in the countyof Wayne and State of Michigan, Improved Pickling-Bath, of which the following is a specification.

This invention relatesto processes for the cleaning of surfaces of iron or steel by means'of pickling baths, and its object is to so chan e the otherwise slowly soluble scales an particles of the higher oxids that they may be quickly absorbed by the pickling solution and therefore offer no continued obs'truction'to the action of the bath on the metal beneath such coverings.

This process'consists in changing the I f patches of scale, rust and other forms of higher oxids on the surfaces of articles of iron and steel being cleaned, by means of a solution of a strong reducing agent, to a ferrous or lower condition when they become readily soluble in the solution of the inorganic acid used to clean the articles,

the reducing agent and the acid preferably being in the same solution, although they m'giy be'in separate solutions.

p and because these tches of scale or rust often occur on the surfaces of articles of iron or steel that are to be cleaned by pickling in an acid bath atches of higher oxid are much more slow y dissolved by the acid than the metal itself, the surfaces that are being pickled are irregularly attacked by iron and steel spotted or. covered with scale elaorgamcl gii illsueh patches of scale usually found on rolled have invented a new and ath is usu ally a sheet metal is slow compared to its action on the bare metal and the sheet metal there-e fore often comes out of the pickling bath very uneven in thickness. By adding sulfurous acid to this bath to 'thli'solution of s lilfuricfhydrochloric or phos horic acid, eithenb blowing sulfur dloxi dfbya ding a sulfite or bisulfite or hyposulfite of sodium, which will be decomposed by the acid, a pickle is obtained that will act substantially equallyon the entire surface being treated The effective sulfurous acid should equal about one fifth of the which is quickly dissolved by the sulfuric acid.

through it effective sulfuric acid but an excess of the Phosphorous acid, hydrogen sulfid and sulfids of iron or sodium may be substituted for the sulfurous acid if desired. Phosv phids of iron or zinc in a sulfuric acid solution liberate phosphin which is also a valuable reducing agent. 1 Solutions ofacid sul fates and acid phosphates may beemployed in place of the solutions of the acids 1 After the metal has been cleaned it may be immediately rinsed in a dilute solution of a roper reducing agent and then dried, or otiierwise treated to prevent the formation of ferric iron.

I claim 2- 1. The process of cleaning surfaces of or rust which consists in treating the same witgi sulfurous acid in a solution of sulfuric ac1 2. The process of cleanin surfaces of iron and steel having patches 0% higher oxids of iron on the metal which consists in immersing the same in a bath wherein the higher oxids will be reduced by sulfurous acid and then absorbed by sulfuric acid which slowly dissolves the metal, removing the articles from the bath and treating them to prevent rusting.

WILLIAM H, ALLEN. 

